Selective atomic layer deposition with post-dose treatment

ABSTRACT

Methods and apparatuses for depositing films in high aspect ratio features and trenches using a post-dose treatment operation during atomic layer deposition are provided. Post-dose treatment operations are performed after adsorbing precursors onto the substrate to remove adsorbed precursors at the tops of features prior to converting the adsorbed precursors to a silicon-containing film. Post-dose treatments include exposure to non-oxidizing gas, exposure to non-oxidizing plasma, and exposure to ultraviolet radiation.

BACKGROUND

Fabrication of devices such as semiconductor devices may involvedeposition of various dielectric, conductive, or semiconductive films inor over raised or recessed features on a substrate. Deposition of filmsthat are conformal to the underlying topography of a substrate can bechallenging, particularly as aspect ratios increase and criticaldimensions of features decrease with fabrication of increasingly smallerdevices.

SUMMARY

Provided herein are methods of processing substrates. One aspectinvolves a method of processing a patterned substrate in a processchamber, the method including: (a) providing the patterned substratehaving one or more features; (b) exposing the patterned substrate to asilicon-containing precursor under conditions allowing thesilicon-containing precursor to adsorb onto surfaces of the one or morefeatures, thereby forming an adsorbed layer of the silicon-containingprecursor over the patterned substrate; (c) before exposing thepatterned substrate to a reactant to form a silicon-containing film andafter exposing the patterned substrate to the silicon-containingprecursor, performing a post-dose treatment operation to preferentiallyremove the adsorbed layer at tops of the one or more features; and (d)exposing the patterned substrate to the reactant and igniting a firstplasma to form the silicon-containing film over the patterned substrate.

In some embodiments, performing the post-dose treatment operationincludes exposing the patterned substrate to a gas such as any ofnitrogen, argon, hydrogen, ammonia, helium, and C_(x)H_(y), where x isan integer between and including 1-5 and y is an integer between andincluding 4-16. In various embodiments, performing the post-dosetreatment operation further includes igniting a second plasma at aplasma power less than about 6 kW. In some embodiments, performing thepost-dose treatment operation further includes applying a bias at a biaspower between 0 W and 1000 W.

In various embodiments, performing the post-dose treatment operationincludes exposing the patterned substrate to ultraviolet radiation at awavelength between about 10 nm and about 400 nm.

In some embodiments, the post-dose treatment operation is performed fora duration between about 0.1 seconds and about 10 seconds.

In various embodiments, the patterned substrate is processed on apedestal, and the silicon-containing film is deposited and the post-dosetreatment operation is performed at a pedestal temperature between about25° C. and about 650° C.

In some embodiments, the silicon-containing film is any of siliconoxide, silicon nitride, and silicon carbide.

In various embodiments, the thickness of the silicon-containing film atthe tops of the one or more features is less than the thickness of thesilicon-containing film at bottoms of the one or more features. In someembodiments, the one or more features have an aspect ratio of at leastabout 2:1. In various embodiments, at least one of the one or morefeatures has a feature opening is less than about 5000 nm wide. In someembodiments, the method also includes repeating (a)-(d) for n cycles,where n is an integer greater than 2. In some embodiments, the processchamber is purged between performing operations (b) and (c). In variousembodiments, the process chamber is purged between performing operations(c) and (d).

Another aspect involves a method of processing a patterned substrate,the method including: (a) providing a patterned substrate having one ormore features; (b) exposing the substrate to a silicon-containingprecursor under conditions allowing the silicon-containing precursor toadsorb onto surfaces of the one or more features, thereby forming anadsorbed layer of the silicon-containing precursor over the patternedsubstrate; (c) before exposing the patterned substrate to a reactant toform a silicon oxide film and after exposing the patterned substrate tothe silicon-containing precursor, performing a post-dose treatmentoperation to preferentially remove the adsorbed layer at tops of the oneor more features, and (d) exposing the patterned substrate to anoxygen-containing reactant and igniting a first plasma to form thesilicon oxide film over the patterned substrate.

In various embodiments, performing the post-dose treatment operationincludes exposing the patterned substrate to a non-oxidizing gas such asany of nitrogen, argon, hydrogen, ammonia, helium, and C_(x)H_(y), wherex is an integer between and including 1-5 and y is an integer betweenand including 4-16. In some embodiments, performing the post-dosetreatment operation further includes igniting a second plasma at aplasma power less than about 6 kW.

In various embodiments, performing the post-dose treatment operationincludes exposing the patterned substrate to ultraviolet radiation at awavelength between about 10 nm and about 400 nm.

Another aspect involves an apparatus for processing substrates, theapparatus including: (a) at least one process chamber including apedestal for holding a substrate having one or more features; (b) atleast one outlet for coupling the at least one process chamber to avacuum; (c) one or more process gas inlets coupled to one or moresilicon-containing precursor sources, one or more post-dose treatmentgas sources, and one or more reactant gas sources; (d) a radio frequency(RF) generator; and (e) a controller for controlling operations in theapparatus, including machine-readable instructions for: (i) introducinga silicon-containing precursor from at least one of the one of the oneor more silicon-containing precursor sources to the at least one processchamber under conditions allowing the silicon-containing precursor toadsorb onto the surface of the substrate, thereby forming an adsorbedlayer of the silicon-containing precursor over the substrate; (ii) priorto introducing a reactant from at least one of the one or more reactantgas sources to the at least one process chamber and after introducingthe silicon-containing precursor, performing a post-dose treatmentoperation to remove adsorbed silicon-containing precursor at tops of theone or more features of the substrate, and (iii) introducing thereactant and igniting a plasma to form a silicon-containing film overthe substrate.

These and other aspects are described further below with reference tothe drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic illustration of a feature in a substrate.

FIG. 1B is an image of features in a substrate.

FIGS. 2A and 2B are images of trenches in substrates.

FIG. 3 is a process flow diagram depicting operations for a method inaccordance with certain disclosed embodiments.

FIGS. 4A-4D are schematic illustrations of substrates during operationsperformed in accordance with certain disclosed embodiments.

FIG. 5 is a timing sequence diagram showing an example of cycles in amethod in accordance with certain disclosed embodiments.

FIG. 6 is a schematic diagram of an example process chamber forperforming certain disclosed embodiments.

FIG. 7 is a schematic diagram of an example process tool for performingcertain disclosed embodiments.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth toprovide a thorough understanding of the presented embodiments. Thedisclosed embodiments may be practiced without some or all of thesespecific details. In other instances, well-known process operations havenot been described in detail to not unnecessarily obscure the disclosedembodiments. While the disclosed embodiments will be described inconjunction with the specific embodiments, it will be understood that itis not intended to limit the disclosed embodiments.

The implementations disclosed below describe methods for depositing amaterial on a substrate such as a wafer, substrate, or other work piece.The work piece may be of various shapes, sizes, and materials. Inaddition to semiconductor wafers, other work pieces that may be usedimplementations disclosed herein include various articles such asprinted circuit boards and the like. The processes and apparatuses canbe used in the fabrication of semiconductor devices, displays, LEDs,photovoltaic panels and the like.

Manufacturing processes of semiconductor devices typically involvedepositing one or more conformal thin films on a substrate in anintegrated fabrication process. For example, some front-end-of-the-lineprocesses may involve deposition of conformal films by atomic layerdeposition (ALD). ALD is a technique that deposits thin layers ofmaterial using sequential self-limiting reactions. ALD processes usesurface-mediated deposition reactions to deposit films on alayer-by-layer basis in cycles. As an example, an ALD cycle may includethe following operations: (i) delivery/adsorption of a precursor, (ii)purging of precursor from the chamber, (iii) delivery of a secondreactant and optionally ignite plasma, and (iv) purging of byproductsfrom the chamber. The reaction between the second reactant and theadsorbed precursor to form a film on the surface of a substrate affectsthe film composition and properties, such as nonuniformity, stress, wetetch rate, dry etch rate, electrical properties (e.g., breakdown voltageand leakage current), etc. In ALD deposition of silicon oxide films,this reaction involves reacting oxygen plasma with carbon and nitrogento form a gaseous species; oxidizing silicon to silicon oxide;eliminating trace carbon, nitrogen, and hydrogen impurities; andincreasing bonding and densification of the film.

Unlike a chemical vapor deposition (CVD) technique, ALD processes usesurface-mediated deposition reactions to deposit films on alayer-by-layer basis. In one example of an ALD process, a substratesurface that includes a population of surface active sites is exposed toa gas phase distribution of a first precursor, such as asilicon-containing precursor, in a dose provided to a chamber housingthe substrate. Molecules of this first precursor are adsorbed onto thesubstrate surface, including chemisorbed species and/or physisorbedmolecules of the first precursor. It should be understood that when thecompound is adsorbed onto the substrate surface as described herein, theadsorbed layer may include the compound as well as derivatives of thecompound. For example, an adsorbed layer of a silicon-containingprecursor may include the silicon-containing precursor as well asderivatives of the silicon-containing precursor. After a first precursordose, the chamber is then evacuated to remove most or all of the firstprecursor remaining in gas phase so that mostly or only the adsorbedspecies remain. In some implementations, the chamber may not be fullyevacuated. For example, the reactor may be evacuated such that thepartial pressure of the first precursor in gas phase is sufficiently lowto mitigate a reaction. A second reactant, such as an oxygen-containingreactant, is introduced to the chamber so that at least some of thesemolecules react with the first precursor adsorbed on the surface. Insome processes, the second precursor reacts immediately with theadsorbed first precursor. In other embodiments, the second reactantreacts only after a source of activation is applied temporally. Forexample, the second reactant may be ignited with the plasma. The chambermay then be evacuated again to remove unbound and/or unreacted secondreactant molecules. As described above, in some embodiments the chambermay not be completely evacuated. Additional ALD cycles may be used tobuild film thickness.

In typical ALD processes, the ALD first precursor dose at leastpartially saturates the substrate surface. In some embodiments, the dosephase of an ALD cycle concludes before the precursor contacts thesubstrate to evenly saturate the surface. Typically, the precursor flowis turned off or diverted at this point, and only purge gas flows. Byoperating in this sub-saturation regime, the ALD process reduces thecycle time and increases throughput. However, because precursoradsorption is not saturation limited, the adsorbed precursorconcentration may vary slightly across the substrate surface. Examplesof ALD processes operating in the sub-saturation regime are provided inU.S. patent application Ser. No. 14/061,587, filed Oct. 23, 2013, titled“SUB-SATURATED ATOMIC LAYER DEPOSITION AND CONFORMAL FILM DEPOSITION,”which is incorporated herein by reference in its entirety.

In some implementations, the ALD methods include plasma activation. Asdescribed herein, the ALD methods and apparatuses described herein maybe conformal film deposition (CFD) methods, which are describedgenerally in U.S. patent application Ser. No. 13/084,399 (now U.S. Pat.No. 8,728,956), filed Apr. 11, 2011, and titled “PLASMA ACTIVATEDCONFORMAL FILM DEPOSITION,” and in U.S. patent application Ser. No.13/084,305, filed Apr. 11, 2011, and titled “SILICON NITRIDE FILMS ANDMETHODS,” which are herein incorporated by reference in theirentireties.

ALD processes may be used for blanket or patterned substrates.Substrates may include “features” or “trenches.” Features may becharacterized by one or more of narrow and/or re-entrant openings,constrictions within the feature, and high aspect ratios. The featuremay be formed in one or more of the above described layers. One exampleof a feature is a hole or via in a semiconductor substrate or a layer onthe substrate. Another example is a trench in a substrate or layer. Theterms “trench” and “feature” may be used interchangeably in the presentdisclosure and will be understood to include any hole, via, or recessedregion of a substrate. In various embodiments, the feature may have anunder-layer, such as a barrier layer or adhesion layer. Non-limitingexamples of under-layers include dielectric layers and conductinglayers, e.g., silicon oxides, silicon nitrides, silicon carbides, metaloxides, metal nitrides, metal carbides, and metal layers.

Films deposited by ALD are typically conformal. Conformality of filmsmay be measured by the step coverage. Step coverage may be calculated bycomparing the average thickness of a deposited film on a bottom,sidewall, or top of a feature or trench to the average thickness of adeposited film on a bottom, sidewall, or top of a feature or trench. Forexample, step coverage may be calculated by dividing the averagethickness of the deposited film on the sidewall by the average thicknessof the deposited film at the top of the feature and multiplying it by100 to obtain a percentage. Although ALD can deposit highly conformalfilms, deposition of films into high aspect ratio features becomeschallenging. The step coverage and uniformity of film property along theside wall depends on, among many factors, the transport of thedeposition precursor, reactant ions and/or radicals, and by-products. Asthe dimension of the feature or trench is reduced, transport anddiffusion of the deposition precursor and reactant becomes increasingdifficult in the feature, thereby leading to formation of a seam and/orvoids in high aspect ratio features.

In plasma-enhanced ALD (PEALD) processes, the top of the trenches toprecursor and reactant species is exposed to more precursor and reactantspecies, while surfaces deeper into a feature are exposed to fewerprecursor and reactant species due to the diffusion of the precursor andreactant species. This differential in molecular interactions at thetop, sidewall, and bottom of the feature leads to non-uniform propertiesalong the sidewall of the feature. For example, in high aspect ratiofeatures, as described above, a void and/or a seam may form in themiddle of the feature. FIG. 1A shows an example of a substrate 100having feature or trench 101 which is filled with silicon oxide 102 by aconventional PEALD technique. A seam 106 forms where the silicon oxidegrowth from the sidewalls of the feature 101 meet, and an air-gap orvoid 160 forms in the center of the feature 101, thereby resulting inincomplete fill of the feature 101. As various PEALD deposition cyclesare performed, the opening at the top of feature 101 closes andmolecular transport becomes progressively difficult, leading toprogressive degradation of the film and closing at the top of thefeature 101, leaving a void 160 in the feature 101. FIG. 1B shows animage of a substrate 110 after exposure to hydrofluoric acid (HF) usedto etch the substrate 110, which causes void 160 to be visible after theetching process.

In addition to the formation of voids and seams, the film depositedwithin the trench may have a different and more degraded film qualitythan the film deposited near the top of a trench. This may be becausethe second reactant species is unable to transport into the depths ofthe trench and the number and distribution of reactant species reachingthe trench bottom is different from and less than at the top. The filmquality can be evaluated by etching the deposited film in diluted HF andobserving and comparing the amount of film etched at or near the top ofthe trenches and the amount of film etched along the sidewalls. Filmshaving a high wet etch rate are more easily etched using HF.

Conventional techniques for increasing exposure time to the secondreactant and plasma to allow more reactant species to diffuse intotrenches have drawbacks. For example, increasing plasma exposure time orplasma power may lead to densification and/or sputtering at the top ofthe features and along corners at or near the top of the features. Anexample is provided in FIGS. 2A and 2B. FIG. 2A shows a substrate with afilm deposited using exposures to cycles of a precursor and 2 -secondexposures to a second reactant ignited with plasma at 495° C. FIG. 2Bshows a substrate with a film deposited using exposures to cycles of aprecursor and 5-second exposures to a second reactant ignited withplasma at 495° C. As shown, the substrate in FIG. 2B has been sputteredat the trench edges 222, resulting in a non-conformal film.

Provided herein are methods and apparatuses for forming films using ALDand or PEALD and post-dose treatments during ALD and/or PEALD cycles.Disclosed embodiments may be used to partially fill high aspect ratiostructures, such as for forming contact liners, and may also be used tocompletely fill high aspect ratio structures, such as for gapfillapplications. Disclosed embodiments may be suitable for depositingsilicon-containing material into high aspect ratio features, such assilicon oxide, silicon, poly-silicon, and silicon nitride.Methods may beused for filling through so it can be us and for 3D NAND applications.Disclosed embodiments reduce deposition at or near the top of featuresor trenches by removing adsorbed precursor from a precursor exposuredose at the top of the features while leaving most of the sidewalls andthe bottom of the features saturated with adsorbed precursor prior toexposing the substrate to a second reactant and igniting a plasma toform a film conformal along most of the sidewalls and at the bottom offeatures while forming a partial or no film at the top of the features.In some embodiments, exposures to an adsorbed precursor layer on asubstrate to a post-dose treatment may be used in the initial ALD orPEALD cycles to allow bottom-up fill of features and trenches andprevent the opening at the top of the features and trenches from closingprior to filling the feature or trench.

FIG. 3 is a process flow diagram depicting operations for a methodperformed in accordance with certain disclosed embodiments. Althoughexamples provided herein describe disclosed embodiments in the contextof depositing silicon oxide films, it should be understood thatdisclosed embodiments may also be used to deposit films of any material.

In operation 302 of FIG. 3, a substrate is provided to a process stationor chamber of a single station or multi-station chamber. Suitableapparatuses for performing certain disclosed embodiments are furtherdescribed below. In various embodiments, the substrate is asemiconductor substrate. The substrate may be a silicon wafer, e.g., a200-mm wafer, a 300-mm wafer, or a 450-mm wafer, such as wafers havingone or more layers of material, such as dielectric, conducting, orsemi-conducting material deposited thereon. Substrates may have featuressuch as via or contact holes, or trenches as previously described. Apatterned substrate may have many features, each having different aspectratios. FIG. 4A shows an example substrate 401 including patternedtrenches or features 403.

In some embodiments, a feature may have an aspect ratio of at leastabout 2:1, at least about 4:1, at least about 6:1, at least about 8:1,at least about 10:1, at least about 20:1, at least about 40:1 or higher.Some features may have a depth of between about 1 μm and about 100 μm,or between about 4 μm and about 100 μm. The feature may also have adimension near the opening, e.g., an opening diameter or line width ofless than about 5000 nm, or between about 25 nm and about 5000 nm, orbetween about 10 nm to 500 nm, or less than about 150 nm.

Some features may be through silicon vias having feature openingsbetween 3 μm and 5 μm and feature depths between 50 μm and 100 μm, andmay have a high aspect ratio, such as at least about 20:1. in someembodiments, NAND structures may have feature openings of 150 to 500 nmand feature depths between 2 μm and 6 μm, and may have an aspect ratioof at least about 40:1.

A via, trench or other recessed feature may be referred to as anunfilled feature or a feature. According to various embodiments, thefeature profile may narrow gradually and/or include an overhang at thefeature opening. A re-entrant profile is one that narrows from thebottom, closed end, or interior of the feature to the feature opening. Are-entrant profile may be generated by asymmetric etching kineticsduring patterning and/or the overhang due to non-conformal film stepcoverage in the previous film deposition, such as deposition of adiffusion barrier. In various examples, the feature may have a widthsmaller in the opening at the top of the feature than the width of thebottom of the feature.

During operations 304-316 of FIG. 3, an inert gas may be flowed. Invarious embodiments, the inert gas is used as a carrier gas. Examplecarrier gases include nitrogen, argon, helium, and neon. In someembodiments, the carrier gas is used as a purge gas in some operations.In some embodiments, the carrier gas is diverted. The inert gas may beprovided to assist with pressure and/or temperature control of theprocess chamber, evaporation of a liquid reactant, more rapid deliveryof the reactant and/or as a sweep gas for removing process gases fromthe process chamber and/or process chamber plumbing.

Disclosed embodiments may be performed at a chamber pressure betweenabout 0.1 Torr and about 20 Torr. In many embodiments, the methodsdisclosed may be performed at a substrate temperature less than about650° C., or less than about 450° C., or between about 50° C. and about650° C., such as about 200° C. It will be understood that substratetemperature as described herein refers to the temperature at which apedestal holding a substrate may be set. In some embodiments, thepedestal may be set to a temperature of less than about 450° C. tocontrol the substrate temperature. In some embodiments, the method isperformed at a higher temperature, such as greater than about 250° C.,or greater than 450° C.

Returning to FIG. 3, in operation 304, the substrate is exposed to adeposition precursor such that the deposition precursor is adsorbed ontothe substrate surface to form an adsorbed layer. FIG. 4B shows anexample substrate 401 including features 403 having been exposed to adeposition precursor (shown at 433 a and 433 b), such that thedeposition precursor molecules conformally adsorbs to the tops,sidewalls, and bottoms of the features.

The deposition precursor may be a silicon-containing precursor in someembodiments. The substrate may be exposed to the deposition precursorfor a duration sufficient to saturate the surface of a substrate havingfeatures, including the bottoms and sidewalls of features. In variousembodiments, the deposition precursor may fully saturate the surface ofthe substrate. In some embodiments, a deposition precursor adsorbs ontothe substrate surface in a self-limiting manner such that once activesites are occupied by the deposition precursor, little or no additionaldeposition precursor will be adsorbed on the substrate surface. Forexample, deposition precursors may be adsorbed onto about 60% of thesubstrate surface. In various embodiments, when the deposition precursoris flowed to the chamber, the deposition precursor adsorbs onto activesites on the surface of the substrate, forming a thin layer of thedeposition precursor on the surface. In various embodiments, this layermay be less than a monolayer, and may have a thickness between about 0.2Å and about 0.4 Å.

A silicon-containing precursor is a single reagent or mixture ofreagents used to make a silicon-containing film, where the reagent orreagent mixture contains at least one silicon compound. In someembodiments, the silicon-containing precursor may be, for example, asilane, a halosilane, or an aminosilane. Where a silicon-containing filmsuch as silicon oxide or silicon nitride, is deposited using disclosedembodiments, various suitable silicon-containing precursors may be used.

Silicon-containing precursors suitable for use in accordance withdisclosed embodiments include polysilanes (H₃Si—(SiH₂)_(n)—SiH₃), wheren≧0. Examples of silanes are silane (SiH₄), disilane (Si₂H₆), andorganosilanes such as methylsilane, ethylsilane, isopropylsilane,t-butylsilane, dimethylsilane, diethylsilane, di-t-butylsilane,allylsilane, sec-butylsilane, thexylsilane, isoamylsilane,t-butyldisilane, di-t-butyldisilane, and the like.

A halosilane includes at least one halogen group and may or may notinclude hydrogens and/or carbon groups. Examples of halosilanes areiodosilanes, bromosilanes, chlorosilanes and fluorosilanes. Althoughhalosilanes, particularly fluorosilanes, may form reactive halidespecies that can etch silicon materials when a plasma is struck, ahalosilane may not be introduced to the chamber when a plasma is struckin some embodiments, so formation of a reactive halide species from ahalosilane may be mitigated. Specific chlorosilanes aretetrachlorosilane, trichlorosilane, dichlorosilane, monochlorosilane,chloroallylsilane, chloromethylsilane, dichloromethylsilane,chlorodimethylsilane, chloroethylsilane, t-butylchlorosilane,di-t-butylchlorosilane, chloroisopropylsilane, chloro- sec-butylsilane,t-butyldimethylchlorosilane, thexyldimethylchlorosilane, and the like.

An aminosilane includes at least one nitrogen atom bonded to a siliconatom, but may also contain hydrogens, oxygens, halogens, and carbons.Examples of aminosilanes are mono-, di-, tri- and tetra-aminosilane(H₃Si(NH₂)₄, H₂Si(NH₂)₂, HSi(NH₂)₃, and Si(NH₂)₄, respectively), as wellas substituted mono-, di-, tri- and tetra-aminosilanes, for example,t-butylaminosilane, methylaminosilane, tert-butylsilanamine,bis(tertiarybutylamino)silane (SiH₂(NHC(CH₃)₃)₂) (BTBAS), tert-butylsilylcarbamate, SiH(CH₃)—(N(CH₃)₂)₂, SiHCl—(N(CH₃)₂)₂, Si(CH₃)₂NH)₃ andthe like. A further example of an aminosilane is trisilylamine(N(SiH₃)).

Returning to FIG. 3, in operation 306, the process chamber is optionallypurged to remove excess deposition precursor in gas phase that did notadsorb onto the surface of the substrate. Purging the chamber mayinvolve flowing one or more purge gases or sweep gases, which may be acarrier gas used in other operations such as described above, or may bea different gas. Example purge gases include argon, nitrogen, hydrogen,and helium. In some embodiments, purging may involve evacuating thechamber. In some embodiments, operation 306 may include one or moreevacuation subphases for evacuating the process chamber. Alternatively,it will be appreciated that operation 306 may be omitted in someembodiments. Operation 306 may have any suitable duration, such asbetween about 0 seconds and about 60 seconds, for example about 0.01seconds. In some embodiments, increasing a flow rate of a one or morepurge gases may decrease the duration of operation 306. For example, apurge gas flow rate may be adjusted according to various reactantthermodynamic characteristics and/or geometric characteristics of theprocess chamber and/or process chamber plumbing for modifying theduration of operation 306. In one non-limiting example, the duration ofa purge phase may be adjusted by modulating purge gas flow rate. Thismay reduce deposition cycle time, which may improve substratethroughput. After a purge, the deposition precursors remain adsorbedonto the substrate surface.

In operation 308, the substrate is exposed to a post-dose treatment topreferentially remove adsorbed deposition precursor molecules from thetop of the features. The “top” of a feature is defined as any region inthe top 10% of the depth of the feature. Exposure to a post-dosetreatment to preferentially remove adsorbed deposition precursormolecules results in a non-continuous, non-conformal adsorbed layer ofprecursor on the substrate such that after the substrate is exposed to apost-dose treatment, the bottom 90% of the depth of the feature (orbottom 80%, or bottom 70%, or bottom 60% of the depth of the feature) isat least about 90% saturated with adsorbed precursor, while little to noprecursors are adsorbed at the top 10% of the features. For example, insome embodiments, the tops of the features have less than about 90%saturation, or less than about 70% saturation, or less than about 30%saturation, or less than about 10% saturation. The amount of saturationat the tops of the features can be modulated to changing processconditions of the post-dose treatment.

The post-dose treatment involves providing energy to the adsorbed layerat the top of the features to break chemical or mechanical bonds betweenthe adsorbed precursor molecules and the underlying material (which maybe semiconductor substrate material or a film deposited in priorcycles), or involves providing energy to the adsorbed layer at the topof the features to disintegrate adsorbed precursor molecules. In someembodiments, the post-dose treatment may physically sputter the adsorbedlayer of precursor molecules particularly at the tops of the features toremove the precursor molecules from being adsorbed to the substratesurface. The post-dose treatment may be performed using a plasmagenerated from nitrogen, argon, hydrogen, ammonia, helium, andC_(x)H_(y) (where x is an integer between and including 1-5 and y is aninteger between and including 4-16 (e.g., x=1-5 and y=4-16)), and/orcombinations thereof, with a bias between 0 W and about 1000 W. Forexample, in some embodiments, a bias may not be used. However, a biasmay be used to control the directionality of the plasma generated duringthe post-dose treatment. The bias may be generated in either a poweredshowerhead or powered pedestal system. In some embodiments, a post-dosetreatment may remove hydroxyl bonds on the surface of the substrate,such as where disclosed embodiments are used for depositing siliconoxide into features. Without being bound by a particular theory, it isbelieved that removal of hydroxyl bonds will prevent adsorption of theprecursor during a subsequent dosing operation (such as in operation 304in a later, repeated cycle of deposition). For example, an aminosilaneprecursor may bind to hydroxyl groups to adsorb onto the surface of thesubstrate, and a post-dose treatment may be used to remove hydroxylbonds and prevent adsorption of the aminosilane precursor in subsequentprecursor adsorption operations.

The post-dose treatment is performed at a substrate temperature betweenabout 25° C. and about 650° C., or between about 25° C. and about 550°C. In some embodiments, where disclosed embodiments are used fordepositing silicon oxide into features, the substrate temperature may bemodulated to prevent formation of a nitride where a nitrogen-containinggas is used in the post-dose treatment. For example, nitrogen may notreact with an adsorbed layer of a silicon-containing precursor at about400° C. so where nitrogen is used as a post-dose treatment, thetemperature may be modulated such that the post-dose treatment isperformed near 400° C., or less than 400° C. to prevent nitrogen fromreacting with the silicon-containing precursor to form silicon nitride.It will be understood that even if a small amount of silicon nitride isformed during the post-dose treatment, when an oxidizing plasma is usedafter the post-dose treatment, the oxidizing plasma will react with thesilicon-containing precursor and any silicon-and-nitrogen-containingintermediate formed on the surface of the substrate to form siliconoxide.

In various embodiments, for depositing a silicon oxide film, thepost-dose treatment includes exposure of the adsorbed precursor layer toan inert non-oxidizing plasma, to ultraviolet (UV) radiation, or both.Exposure to a non-oxidizing plasma may be facilitated by generating aplasma in a remote plasma generator or generating a plasma in theprocessing chamber where the substrate is being processed. Anon-oxidizing gas is flowed to a plasma generating region, which may bethe remote plasma generator or the processing chamber, and a plasma isignited. The non-oxidizing gas may be any of nitrogen, argon, hydrogen,ammonia, helium, and C_(x)H_(y) (where x=1-5, and y=4-16), and/orcombinations thereof.

Process conditions including the plasma power, plasma frequency,exposure time to a non-oxidizing plasma, flow rate of the non-oxidizinggas, chamber pressure, and pedestal temperature may be modulated toprevent formation of silicon nitride if nitrogen or ammonia is used as anon-oxidizing gas for post-dose treatments in processes used to depositsilicon oxide. In some embodiments, silicon nitride may form on thesurface of the substrate during a post-dose treatment, but due to thebond energies of silicon to oxygen and silicon to nitrogen, wheresilicon oxide is formed in subsequent operations, silicon nitride can beconverted to oxide. Process conditions are modulated to avoid formationof conversion plasmas, such as an oxygen plasma for forming oxide,ammonia plasma for forming nitride, and carbon-containing plasma forforming carbide. In some embodiments, an intermediate compound may formduring post-dose treatment. For example, an intermediate compound mayinclude silicon atoms bound to nitrogen atoms from a nitrogen or ammoniapost-dose treatment. Even if an intermediate compound is formed, plasmais generated at low energy such that the intermediate species convertsto the desired film to be deposited when exposed to the plasma. Forexample, where silicon oxide is being deposited into a feature, oxygenplasma may be used after a post-dose treatment such that even if anintermediate compound is formed after post-dose treatment, the oxygenplasma will convert the intermediate compound into silicon oxide.

The plasma in operation 308 may be generated at a power at less thanabout 6 kW, or between about 500 W and about 4000 W. The post-dosetreatment when using a gas or plasma may be performed for a durationbetween about 0.1 seconds and about 10 seconds, or between about 0.3seconds and about 3 seconds.

In some embodiments, the non-oxidizing gas or post-dose treatment gasmay be used without generating a plasma. A post-dose treatment performedusing ultraviolet radiation may be performed by exposing the substrateto UV light having a wavelength between about 10 nm and about 400 nm.The substrate may be exposed to ultraviolet radiation for a durationbetween about 0.1 seconds and about 10 seconds. The duration andwavelength of UV light used depends on the precursor used and the aspectratio of the features on the substrate.

FIG. 4C shows an example substrate 401 having features 403 where some ofthe adsorbed precursor molecules at the top of the features 403 areremoved, while the adsorbed precursor on the bottoms and sidewalls 413of the features 403 remain adsorbed to the substrate.

Returning to FIG. 3, in operation 310, the process chamber is optionallypurged to remove the removed adsorbed precursor molecules from thepost-dose treatment process. Purging may involve any of the processesand process conditions described above with respect to operation 306.

In operation 312, the substrate is exposed to a reactant and a plasma isignited such that the adsorbed silicon-containing precursor layerremaining on the surface of the substrate is converted to the desiredfilm, such as silicon oxide. Note that the term “reactant” or “secondreactant” may be used to describe one or more gases introduced to thechamber when plasma is ignited in a deposition cycle. In variousembodiments, the second reactant is an oxygen-containing reactant oroxidant, to form at least a partial silicon oxide film on the surface ofthe substrate. This operation may be performed for a duration betweenabout 0.05 seconds and about 10 seconds. The duration of this operationmay be modulated depending on the depth of the trench or feature wherematerial is being deposited, and depending on the number of cycles usedas further described below with respect to operation 316.

In various embodiments, during operation 312, plasma energy is providedto activate the second reactant, such as an oxygen-containing gas, intoions, radicals, neutral species, and other activated species, whichreact with the remaining adsorbed layer of the silicon-containingdeposition precursor. For example, the plasma may directly or indirectlyactivate the oxygen-containing gas phase molecules to form oxygenradicals or ions. Conditions of the chamber may be monitored such thatsufficient plasma species can diffuse into trenches and tailor thefeature profile and improve conformality within features and trenches.

In various embodiments, the plasma is an in-situ plasma, such that theplasma is formed directly above the substrate surface in the chamber.The in-situ plasma may be ignited at a power per substrate area betweenabout 0.2122 W/cm² and about 2.122 W/cm². For example, the power mayrange from about 150 W to about 6000 W, or from about 600 W to about6000 W, or from about 800 W to about 4000 W, for a chamber processingfour 300 mm wafers. For example, plasmas for ALD processes may begenerated by applying a radio frequency (RF) field to a gas using twocapacitively coupled plates. Ionization of the gas between plates by theRF field ignites the plasma, creating free electrons in the plasmadischarge region. These electrons are accelerated by the RF field andmay collide with gas phase reactant molecules. Collision of theseelectrons with reactant molecules may form radical species thatparticipate in the deposition process. It will be appreciated that theRF field may be coupled via any suitable electrodes. In variousembodiments, a high frequency plasma is used having a frequency of atleast about 13.56 MHz, or at least about 27 MHz, or at least about 40MHz, or at least about 60 MHz. In some embodiments, a microwave-basedplasma may be used. Non-limiting examples of electrodes include processgas distribution showerheads and substrate support pedestals. It will beappreciated that plasmas for ALD processes may be formed by one or moresuitable methods other than capacitive coupling of an RF field to a gas.In some embodiments, the plasma is a remote plasma, such that a secondreactant is ignited in a remote plasma generator upstream of thechamber, then delivered to the chamber where the substrate is housed.

Example oxygen-containing reactants or oxidants include a mixture ofoxygen and a weak oxidizer such as nitrous oxide, carbon monoxide,carbon dioxide, nitric oxide, nitrogen dioxide, sulfur oxide, sulfurdioxide, oxygen-containing hydrocarbons (e.g., C_(x)H_(y) O_(z)) and/orwater. In other implementations, the oxidation reactant may be entirelyweak oxidizer. Alternatively, the oxidation reactant may include ozone.

For deposition of other silicon-containing materials, other reactantsmay be used as the second reactant to deposit films of differentmaterials. For example, for deposition of a silicon carbide film usingdisclosed embodiments, the second reactant may be a carbon-containingreactant. For example, for deposition of silicon nitride, anitrogen-containing reactant may be used. A nitrogen-containing reactantis a reactant or mixture of reactants that includes at least onenitrogen, for example, ammonia, hydrazine, amines (amines bearingcarbon) such as methylamine, dimethylamine, ethylamine, isopropylamine,t-butylamine, di-t-butylamine, cyclopropylamine, sec-butylamine,cyclobutylamine, isoamylamine, 2-methylbutan-2-amine, trimethylamine,diisopropylamine, diethylisopropylamine, di-t-butylhydrazine, as well asaromatic containing amines such as anilines, pyridines, andbenzylamines. Amines may be primary, secondary, tertiary, or quaternary(for example, tetraalkylammonium compounds). A nitrogen-containingreactant can contain heteroatoms other than nitrogen, for example,hydroxylamine, t-butyloxycarbonyl amine, and N-t-butyl hydroxylamine arenitrogen-containing reactants. Example nitrogen-containing reactantsinclude nitrogen gas, ammonia, and amines. For deposition a doped film,a dopant may also be added as a second reactant.

FIG. 4D shows an example substrate 401 with trenches or features 403whereby the substrate has been exposed a second reactant with a plasmaand the adsorbed layer of precursor molecules has been reacted andconverted to form a film 450 on the substrate, where the film 450 ispreferentially deposited along the sidewalls and the bottom of thetrenches, while little to no deposition of the film is formed over thetop 424 of the features 403. In various embodiments, the thickness ofthe deposited silicon-containing film is less than the thickness of thedeposited silicon-containing film at the bottoms of the features.

Returning to FIG. 3, in operation 314, the process chamber is optionallypurged to remove any residual byproducts. Purging may involve any of theprocesses and process conditions described above with respect tooperation 306.

In operation 316 of FIG. 3, it is determined whether the desiredthickness of film has been deposited. If not, operations 304-314 arerepeated in sufficient cycles to deposit a desired thickness of film.Any suitable number of deposition cycles may be included in a process todeposit a desired film thickness of the desired film in accordance withcertain disclosed embodiments. In various embodiments, operations may berepeated for n cycles, where n is an integer greater than or equal to 2.For example, in some embodiments, operations 304-314 may be repeated fortwo or more cycles.

The frequency of performing the post-dose treatment of operation 308 topreferentially remove adsorbed precursor at the top of the features maydepend on the size of the features and the amount of film to bedeposited in the features. As noted above, exposure to a post-dosetreatment may not necessarily be performed in every cycle. In later,repeated cycles, as the trench depth decreases (e.g., as the trench isfilled with material such as silicon oxide), the frequency of performinga post-dose treatment may be modified or reduced. For example, as thetrench fills with silicon oxide, the aspect ratio of the remainingfeature to be filled with silicon oxide decreases and the post-dosetreatment may not need to be performed to avoid formation of a void.

The duration of operation 312 may depend on the size of the feature ortrench to be filled and may be reduced in later repeated depositioncycles. For example, in some embodiments, the initial cycles ofperforming disclosed embodiments may use a longer duration of operation312 (such as between about 0.1 seconds and about 10 seconds) to allowdiffusion of the second reactant plasma into trenches and features toreach with adsorbed precursor at the bottom and sidewalls of trenchesand features. In later cycles where the trenches and features are atleast about 30% filled, the duration of operation 312 may be graduallyreduced as the distance the second reactant plasma travels to diffuse tothe adsorbed layer of precursor molecules decreases. In some latercycles where the trenches and features are at least about 80% filled,the post-dose treatment operation may not be performed in every cycle,or in any cycle.

FIG. 5 is a timing sequence diagram of example pulses in accordance withcertain disclosed embodiments. FIG. 5 shows phases in an example ALDprocess 500 for various process parameters, such as carrier gas flow,first precursor flow, post-dose treatment gas flow, plasma, and secondreactant flow. The lines indicate when the flow or plasma is turned onand off, accordingly. Additional example process parameters include, butare not limited to, flow rates for inert and reactant species, plasmapower and frequency, substrate temperature, and process chamberpressure. The example provided in FIG. 5 depicts two deposition cycles590A and 590B for depositing a silicon oxide film using asilicon-containing precursor and oxygen plasma, and a non-oxidizingplasma is used for post-dose treatment.

Two deposition cycles 590A and 590B are depicted. Each deposition cycleincludes various phases. For example, deposition cycle 590A includes asilicon precursor exposure phase 504A, which may correspond to operation304 of FIG. 3; a purge phase 506A (which may be optional and maycorrespond to operation 306 of FIG. 3); a post-dose treatment phase508A, which may correspond to operation 308 of FIG. 3; a purge phase510A (which may be optional and may correspond to operation 310 of FIG.3); an oxygen plasma exposure phase 512A, which may correspond tocombining operation 312 in FIG. 3; and purge phase 514A which maycorrespond to operation 314 of FIG. 3. As shown in example process 500,a carrier gas is flowed throughout the process. It will be understoodthat any suitable carrier gas may be used as describe elsewhere herein.In various embodiments, the carrier gas is used as a purge gas. Inprocess 500, the carrier gas is depicted as being both a carrier gas anda purge gas during pure phases 506A, 510A, 514A, 506B, 510B, and 514B.In some embodiments, the carrier gas may be different than the purgegas. In some embodiments, a carrier gas is only flowed during one ormore of the purge phases ( 506A, 510A, 514A, 506B, 510B, and 514B). Acarrier gas may be any of those described above with respect tooperation 306 of FIG. 3.

In silicon precursor exposure phase 504A, which may correspond tooperation 304 of FIG. 3, a silicon-containing precursor is flowed with acarrier gas and oxygen flow is turned off. The plasma is also turnedoff, and non-oxidizing gas flow is also turned off. In purge phase 506A,all gas flows except the carrier gas are turned off and the plasma isturned off. This may correspond to operation 306 of FIG. 3. In post-dosetreatment phase 508A, the carrier gas remains on, the non-oxidizing gasflow is turned on, and the plasma is turned on to generate anon-oxidizing plasma to preferentially remove adsorbedsilicon-containing precursor molecules at or near the top of features.The silicon-containing precursor and oxygen gas flows are turned off.This may correspond to operation 308 of FIG. 3. In purge phase 510A, allgas flows except the carrier gas are turned off and the plasma is turnedoff. This may correspond to operation 310 of FIG. 3. In oxygen plasmaexposure phase 512A, the carrier gas is flowed with the oxygen flow,while the plasma is turned on to ignite and generate andoxygen-containing plasma. This oxygen-containing plasma reacts with theremaining adsorbed precursor to selectively form silicon oxide alongsidewalls and the bottom of trenches while forming little to no siliconoxide at or near the tops of the trenches. This operation may correspondto combining operations 312 of FIG. 3. In purge phase 514A, the carriergas flow remains on and all other gas flows and plasma is turned off.

In example process 500, it is determined in operation 316 of FIG. 3 thatthe film deposited is not an adequate thickness or the desiredthickness, so the deposition cycle is repeated in deposition cycle 590B.In this example, deposition cycle 590B includes silicon-containingexposure phase 504, purge phase 506B (which may be optional), post-dosetreatment phase 508B, purge phase 510B (which may be optional), oxygenplasma exposure phase 512B, and purge phase 514B (which may beoptional).

Apparatus

FIG. 6 depicts a schematic illustration of an embodiment of an atomiclayer deposition (ALD) process station 600 having a process chamber 602for maintaining a low-pressure environment. A plurality of ALD processstations may be included in a common low pressure process toolenvironment. For example, FIG. 7 depicts an embodiment of amulti-station processing tool 700. In some embodiments, one or morehardware parameters of ALD process station 600, including thosediscussed in detail below, may be adjusted programmatically by one ormore computer controllers 650.

ALD process station 600 fluidly communicates with reactant deliverysystem 601 a for delivering process gases to a distribution showerhead606. Reactant delivery system 601 a includes a mixing vessel 604 forblending and/or conditioning process gases, such as a silicon-containinggas, or oxygen-containing gas, or post-dose treatment gases such asnon-oxidizing gases, for delivery to showerhead 606. One or more mixingvessel inlet valves 620 may control introduction of process gases tomixing vessel 604. The mixing vessel 604 may also be used for blendingpost-dose treatment gases such as argon, hydrogen, nitrogen, ammonia,C_(x)H_(y) (where x=1-5, and y=4-16), and/or combinations thereof. Invarious embodiments, the post-dose treatment is performed in processstation 600 and the film deposition is also performed in the sameprocess station 600. For example, in some embodiments, the ALD processstation 600 may be used to deliver a deposition precursor gas to theprocess chamber 602, then deliver a non-oxidizing gas and ignite aplasma to preferentially remove adsorbed precursor on a substrate, thendeliver a second reactant and ignite a plasma to convert remainingadsorbed precursors on the substrate to a film such as silicon oxide. Insome embodiments, the post-dose treatment is performed in a processstation separate from the ALD process station 600, such as in anotherstation of the multi-station processing tool 700 as further describedbelow with respect to FIG. 7.

As an example, the embodiment of FIG. 6 includes a vaporization point603 for vaporizing liquid reactant to be supplied to the mixing vessel604. In some embodiments, vaporization point 603 may be a heatedvaporizer. The saturated reactant vapor produced from such vaporizersmay condense in downstream delivery piping. Exposure of incompatiblegases to the condensed reactant may create small particles. These smallparticles may clog piping, impede valve operation, contaminatesubstrates, etc. Some approaches to addressing these issues involvepurging and/or evacuating the delivery piping to remove residualreactant. However, purging the delivery piping may increase processstation cycle time, degrading process station throughput. Thus, in someembodiments, delivery piping downstream of vaporization point 603 may beheat traced. In some examples, mixing vessel 604 may also be heattraced. In one non-limiting example, piping downstream of vaporizationpoint 603 has an increasing temperature profile extending fromapproximately 100° C. to approximately 150° C. at mixing vessel 604.

In some embodiments, a liquid precursor or liquid reactant may bevaporized at a liquid injector (not shown). For example, a liquidinjector may inject pulses of a liquid reactant into a carrier gasstream upstream of the mixing vessel 604. In one embodiment, a liquidinjector may vaporize the reactant by flashing the liquid from a higherpressure to a lower pressure. In another example, a liquid injector mayatomize the liquid into dispersed microdroplets that are subsequentlyvaporized in a heated delivery pipe. Smaller droplets may vaporizefaster than larger droplets, reducing a delay between liquid injectionand complete vaporization. Faster vaporization may reduce a length ofpiping downstream from vaporization point 603. In one scenario, a liquidinjector may be mounted directly to mixing vessel 604. In anotherscenario, a liquid injector may be mounted directly to showerhead 606.

In some embodiments, a liquid flow controller (LFC) upstream ofvaporization point 603 may be provided for controlling a mass flow ofliquid for vaporization and delivery to process chamber 602. Forexample, the LFC may include a thermal mass flow meter (MFM) locateddownstream of the LFC. A plunger valve of the LFC may then be adjustedresponsive to feedback control signals provided by aproportional-integral-derivative (PID) controller in electricalcommunication with the MFM. However, it may take one second or more tostabilize liquid flow using feedback control. This may extend a time fordosing a liquid reactant. Thus, in some embodiments, the LFC may bedynamically switched between a feedback control mode and a directcontrol mode. In some embodiments, this may be performed by disabling asense tube of the LFC and the PID controller.

Showerhead 606 distributes process gases toward substrate 612. In theembodiment shown in FIG. 6, the substrate 612 is located beneathshowerhead 606 and is shown resting on a pedestal 608. Showerhead 606may have any suitable shape, and may have any suitable number andarrangement of ports for distributing process gases to substrate 612.

In some embodiments, pedestal 608 may be raised or lowered to exposesubstrate 612 to a volume between the substrate 612 and the showerhead606. In some embodiments, pedestal 608 may be temperature controlled viaheater 610. Pedestal 608 may be set to any suitable temperature, such asbetween about 25° C. and about 650° C. during operations for performingvarious disclosed embodiments. It will be appreciated that, in someembodiments, pedestal height may be adjusted programmatically by asuitable computer controller 650.

In another scenario, adjusting a height of pedestal 608 may allow aplasma density to be varied during plasma activation cycles andpost-dose treatment operations performed in certain disclosedembodiments. At the conclusion of a process phase, pedestal 608 may belowered during another substrate transfer phase to allow removal ofsubstrate 612 from pedestal 608.

In some embodiments, a position of showerhead 606 may be adjustedrelative to pedestal 608 to vary a volume between the substrate 612 andthe showerhead 606. Further, it will be appreciated that a verticalposition of pedestal 608 and/or showerhead 606 may be varied by anysuitable mechanism within the scope of the present disclosure. In someembodiments, pedestal 608 may include a rotational axis for rotating anorientation of substrate 612. It will be appreciated that, in someembodiments, one or more of these example adjustments may be performedprogrammatically by one or more suitable computer controllers 650. Thecomputer controller 650 may include any of the features described belowwith respect to controller 750 of FIG. 7.

In some embodiments where plasma may be used as discussed above,showerhead 606 and pedestal 608 electrically communicate with a radiofrequency (RF) power supply 614 and matching network 616 for powering aplasma. In some embodiments, the plasma energy may be controlled bycontrolling one or more of a process station pressure, a gasconcentration, an RF source power, an RF source frequency, and a plasmapower pulse timing. For example, RF power supply 614 and matchingnetwork 616 may be operated at any suitable power to form a plasmahaving a desired composition of radical species. Examples of suitablepowers are included above. Likewise, RF power supply 614 may provide RFpower of any suitable frequency. In some embodiments, RF power supply614 may be configured to control high- and low-frequency RF powersources independently of one another. Example low-frequency RFfrequencies may include, but are not limited to, frequencies between 0kHz and 500 kHz. Example high-frequency RF frequencies may include, butare not limited to, frequencies between 1.8 MHz and 2.45 GHz, or greaterthan about 13.56 MHz, or greater than 27MHz, or greater than 40 MHz, orgreater than 60 MHz. It will be appreciated that any suitable parametersmay be modulated discretely or continuously to provide plasma energy forthe surface reactions. The plasma conditions may be controlled and/ormaintained such that plasma generated for a post-dose treatmentoperation preferentially removes adsorbed precursor molecules at or nearfeature openings rather than in sidewalls or at the bottom of features.In one non-limiting example, the plasma power may be intermittentlypulsed to reduce ion bombardment with the substrate surface relative tocontinuously powered plasmas.

In some embodiments, the plasma may be monitored in-situ by one or moreplasma monitors. In one scenario, plasma power may be monitored by oneor more voltage, current sensors (e.g., VI probes). In another scenario,plasma density and/or process gas concentration may be measured by oneor more optical emission spectroscopy sensors (OES). In someembodiments, one or more plasma parameters may be programmaticallyadjusted based on measurements from such in-situ plasma monitors. Forexample, an OES sensor may be used in a feedback loop for providingprogrammatic control of plasma power. It will be appreciated that, insome embodiments, other monitors may be used to monitor the plasma andother process characteristics. Such monitors may include, but are notlimited to, infrared (IR) monitors, acoustic monitors, and pressuretransducers.

In some embodiments, instructions for a controller 650 may be providedvia input/output control (IOC) sequencing instructions. In one example,the instructions for setting conditions for a process phase may beincluded in a corresponding recipe phase of a process recipe. In somecases, process recipe phases may be sequentially arranged, so that allinstructions for a process phase are executed concurrently with thatprocess phase. In some embodiments, instructions for setting one or morereactor parameters may be included in a recipe phase. For example, afirst recipe phase may include instructions for setting a flow rate ofan inert and/or a reactant gas (e.g., the first precursor such as asilicon-containing precursor), instructions for setting a flow rate of acarrier gas (such as argon), and time delay instructions for the firstrecipe phase. A second, subsequent recipe phase may include instructionsfor modulating or stopping a flow rate of an inert and/or a reactantgas, and instructions for modulating a flow rate of a carrier or purgegas and time delay instructions for the second recipe phase. A thirdrecipe phase may include instructions for modulating a flow rate of apost-dose treatment gas such as nitrogen when the process is programmedto deposit silicon oxide, instructions for modulating the flow rate of acarrier or purge gas, instructions for igniting a plasma, and time delayinstructions for the third recipe phase. A fourth, subsequent recipephase may include instructions for modulating or stopping a flow rate ofan inert and/or a post-dose treatment gas, and instructions formodulating a flow rate of a carrier or purge gas and time delayinstructions for the fourth recipe phase. A fifth recipe phase mayinclude instructions for modulating a flow rate of a second reactant gassuch as oxygen, instructions for modulating the flow rate of a carrieror purge gas, instructions for igniting a plasma, and time delayinstructions for the fifth recipe phase. A sixth, subsequent recipephase may include instructions for modulating or stopping a flow rate ofan inert and/or a reactant gas, and instructions for modulating a flowrate of a carrier or purge gas and time delay instructions for the sixthrecipe phase. It will be appreciated that these recipe phases may befurther subdivided and/or iterated in any suitable way within the scopeof the present disclosure.

Further, in some embodiments, pressure control for process station 600may be provided by butterfly valve 618. As shown in the embodiment ofFIG. 6, butterfly valve 618 throttles a vacuum provided by a downstreamvacuum pump (not shown). However, in some embodiments, pressure controlof process station 600 may also be adjusted by varying a flow rate ofone or more gases introduced to the process station 600.

As described above, one or more process stations may be included in amulti-station processing tool. FIG. 7 shows a schematic view of anembodiment of a multi-station processing tool 700 with an inbound loadlock 702 and an outbound load lock 704, either or both of which mayinclude a remote plasma source (not shown). A robot 706, at atmosphericpressure, is configured to move wafers from a cassette loaded through apod 708 into inbound load lock 702 via an atmospheric port 710. A wafer(not shown) is placed by the robot 706 on a pedestal 712 in the inboundload lock 702, the atmospheric port 710 is closed, and the load lockinbound 702 is pumped down. Where the inbound load lock 702 includes aremote plasma source, the wafer may be exposed to a remote plasmatreatment in the inbound load lock 702 prior to being introduced into aprocessing chamber 714. Further, the wafer also may be heated in theinbound load lock 702 as well, for example, to remove moisture andadsorbed gases. Next, a chamber transport port 716 to processing chamber714 is opened, and another robot (not shown) places the wafer into thereactor on a pedestal of a first station shown in the reactor forprocessing. While the embodiment depicted in FIG. 7 includes load locks,it will be appreciated that, in some embodiments, direct entry of awafer into a process station may be provided.

The depicted processing chamber 714 includes four process stations,numbered from 1 to 4 in the embodiment shown in FIG. 7. Each station hasa heated pedestal (shown at 718 for station 1), and gas line inlets. Itwill be appreciated that in some embodiments, each process station mayhave different or multiple purposes. For example, in some embodiments, aprocess station may be switchable between an ALD and plasma-enhanced ALDprocess mode. In another example, post-dose treatment operations may beperformed in one station, while exposure to a deposition precursor andexposure to a second reactant and plasma may be performed in anotherstation. In some embodiments, exposure to a deposition precursor,post-dose treatment, and exposure to a second reactant and plasma areperformed in the same station. Additionally or alternatively, in someembodiments, processing chamber 714 may include one or more matchedpairs of ALD and plasma-enhanced ALD process stations. While thedepicted processing chamber 714 includes four stations, it will beunderstood that a processing chamber according to the present disclosuremay have any suitable number of stations. For example, in someembodiments, a processing chamber may have five or more stations, whilein other embodiments a processing chamber may have three or fewerstations.

FIG. 7 depicts an embodiment of a wafer handling system 790 fortransferring wafers within processing chamber 714. In some embodiments,wafer handling system 790 may transfer wafers between various processstations and/or between a process station and a load lock. It will beappreciated that any suitable wafer handling system may be employed.Non-limiting examples include wafer carousels and wafer handling robots.FIG. 7 also depicts an embodiment of a system controller 750 employed tocontrol process conditions and hardware states of process tool 700.System controller 750 may include one or more memory devices 756, one ormore mass storage devices 754, and one or more processors 752. Processor752 may include a CPU or computer, analog, and/or digital input/outputconnections, stepper motor controller boards, etc.

In some embodiments, system controller 750 controls all of theactivities of process tool 700. System controller 750 executes systemcontrol software 758 stored in mass storage device 754, loaded intomemory device 756, and executed on processor 752. Alternatively, thecontrol logic may be hard coded in the controller 750. ApplicationsSpecific Integrated Circuits, Programmable Logic Devices (e.g.,field-programmable gate arrays, or FPGAs) and the like may be used forthese purposes. In the following discussion, wherever “software” or“code” is used, functionally comparable hard coded logic may be used inits place. System control software 758 may include instructions forcontrolling the timing, mixture of gases, gas flow rates, chamber and/orstation pressure, chamber and/or station temperature, wafer temperature,target power levels, RF power levels, substrate pedestal, chuck and/orsusceptor position, and other parameters of a particular processperformed by process tool 700. System control software 758 may beconfigured in any suitable way. For example, various process toolcomponent subroutines or control objects may be written to controloperation of the process tool components used to carry out variousprocess tool processes. System control software 758 may be coded in anysuitable computer readable programming language.

In some embodiments, system control software 758 may includeinput/output control (IOC) sequencing instructions for controlling thevarious parameters described above. Other computer software and/orprograms stored on mass storage device 754 and/or memory device 756associated with system controller 750 may be employed in someembodiments. Examples of programs or sections of programs for thispurpose include a substrate positioning program, a process gas controlprogram, a pressure control program, a heater control program, and aplasma control program.

A substrate positioning program may include program code for processtool components that are used to load the substrate onto pedestal 718and to control the spacing between the substrate and other parts ofprocess tool 700.

A process gas control program may include code for controlling gascomposition (e.g., silicon-containing gases, oxygen-containing gases,gases for performing a post-dose treatment, and purge gases as describedherein) and flow rates and optionally for flowing gas into one or moreprocess stations prior to deposition in order to stabilize the pressurein the process station. A pressure control program may include code forcontrolling the pressure in the process station by regulating, forexample, a throttle valve in the exhaust system of the process station,a gas flow into the process station, etc.

A heater control program may include code for controlling the current toa heating unit that is used to heat the substrate. Alternatively, theheater control program may control delivery of a heat transfer gas (suchas helium) to the substrate.

A plasma control program may include code for setting RF power levelsapplied to the process electrodes in one or more process stations inaccordance with the embodiments herein.

A pressure control program may include code for maintaining the pressurein the reaction chamber in accordance with the embodiments herein.

In some embodiments, there may be a user interface associated withsystem controller 750. The user interface may include a display screen,graphical software displays of the apparatus and/or process conditions,and user input devices such as pointing devices, keyboards, touchscreens, microphones, etc.

In some embodiments, parameters adjusted by system controller 750 mayrelate to process conditions. Non-limiting examples include process gascomposition and flow rates, temperature, pressure, plasma conditions(such as RF bias power levels), pressure, temperature, etc. Theseparameters may be provided to the user in the form of a recipe, whichmay be entered utilizing the user interface.

Signals for monitoring the process may be provided by analog and/ordigital input connections of system controller 750 from various processtool sensors. The signals for controlling the process may be output onthe analog and digital output connections of process tool 700.Non-limiting examples of process tool sensors that may be monitoredinclude mass flow controllers, pressure sensors (such as manometers),thermocouples, etc. Appropriately programmed feedback and controlalgorithms may be used with data from these sensors to maintain processconditions.

System controller 750 may provide program instructions for implementingthe above-described deposition processes. The program instructions maycontrol a variety of process parameters, such as DC power level, RF biaspower level, pressure, temperature, etc. The instructions may controlthe parameters to operate in-situ deposition of film stacks according tovarious embodiments described herein.

The system controller 750 will typically include one or more memorydevices and one or more processors configured to execute theinstructions so that the apparatus will perform a method in accordancewith disclosed embodiments. Machine-readable media containinginstructions for controlling process operations in accordance withdisclosed embodiments may be coupled to the system controller 750.

In some implementations, the system controller 750 is part of a system,which may be part of the above-described examples. Such systems caninclude semiconductor processing equipment, including a processing toolor tools, chamber or chambers, a platform or platforms for processing,and/or specific processing components (a wafer pedestal, a gas flowsystem, etc.). These systems may be integrated with electronics forcontrolling their operation before, during, and after processing of asemiconductor wafer or substrate. The electronics may be referred to asthe “controller,” which may control various components or subparts ofthe system or systems. The system controller 750, depending on theprocessing conditions and/or the type of system, may be programmed tocontrol any of the processes disclosed herein, including the delivery ofprocessing gases, temperature settings (e.g., heating and/or cooling),pressure settings, vacuum settings, power settings, radio frequency (RF)generator settings, RF matching circuit settings, frequency settings,flow rate settings, fluid delivery settings, positional and operationsettings, wafer transfers into and out of a tool and other transfertools and/or load locks connected to or interfaced with a specificsystem.

Broadly speaking, the system controller 750 may be defined aselectronics having various integrated circuits, logic, memory, and/orsoftware that receive instructions, issue instructions, controloperation, enable cleaning operations, enable endpoint measurements, andthe like. The integrated circuits may include chips in the form offirmware that store program instructions, digital signal processors(DSPs), chips defined as application specific integrated circuits(ASICs), and/or one or more microprocessors, or microcontrollers thatexecute program instructions (e.g., software). Program instructions maybe instructions communicated to the system controller 750 in the form ofvarious individual settings (or program files), defining operationalparameters for carrying out a particular process on or for asemiconductor wafer or to a system. The operational parameters may, insome embodiments, be part of a recipe defined by process engineers toaccomplish one or more processing steps during the fabrication of one ormore layers, materials, metals, oxides, silicon, silicon dioxide,surfaces, circuits, and/or dies of a wafer.

The system controller 750, in some implementations, may be a part of orcoupled to a computer that is integrated with, coupled to the system,otherwise networked to the system, or a combination thereof. Forexample, the system controller 750 may be in the “cloud” or all or apart of a fab host computer system, which can allow for remote access ofthe wafer processing. The computer may enable remote access to thesystem to monitor current progress of fabrication operations, examine ahistory of past fabrication operations, examine trends or performancemetrics from a plurality of fabrication operations, to change parametersof current processing, to set processing steps to follow a currentprocessing, or to start a new process. In some examples, a remotecomputer (e.g. a server) can provide process recipes to a system over anetwork, which may include a local network or the Internet. The remotecomputer may include a user interface that enables entry or programmingof parameters and/or settings, which are then communicated to the systemfrom the remote computer. In some examples, the system controller 750receives instructions in the form of data, which specify parameters foreach of the processing steps to be performed during one or moreoperations. It should be understood that the parameters may be specificto the type of process to be performed and the type of tool that thesystem controller 750 is configured to interface with or control. Thusas described above, the system controller 750 may be distributed, suchas by including one or more discrete controllers that are networkedtogether and working towards a common purpose, such as the processes andcontrols described herein. An example of a distributed controller forsuch purposes would be one or more integrated circuits on a chamber incommunication with one or more integrated circuits located remotely(such as at the platform level or as part of a remote computer) thatcombine to control a process on the chamber.

Without limitation, example systems may include a plasma etch chamber ormodule, a deposition chamber or module, a spin-rinse chamber or module,a metal plating chamber or module, a clean chamber or module, a beveledge etch chamber or module, a physical vapor deposition (PVD) chamberor module, a chemical vapor deposition (CVD) chamber or module, an ALDchamber or module, an atomic layer etch (ALE) chamber or module, an ionimplantation chamber or module, a track chamber or module, and any othersemiconductor processing systems that may be associated or used in thefabrication and/or manufacturing of semiconductor wafers.

As noted above, depending on the process step or steps to be performedby the tool, the system controller 750 might communicate with one ormore of other tool circuits or modules, other tool components, clustertools, other tool interfaces, adjacent tools, neighboring tools, toolslocated throughout a factory, a main computer, another controller, ortools used in material transport that bring containers of wafers to andfrom tool locations and/or load ports in a semiconductor manufacturingfactory.

An appropriate apparatus for performing the methods disclosed herein isfurther discussed and described in U.S. patent application Ser. No.13/084,399 (now U.S. Pat. No. 8,728,956), filed Apr. 11, 2011, andtitled “PLASMA ACTIVATED CONFORMAL FILM DEPOSITION”; and U.S. patentapplication Ser. No. 13/084,305, filed Apr. 11, 2011, and titled“SILICON NITRIDE FILMS AND METHODS,” each of which is incorporatedherein in its entireties.

The apparatus/process described herein may be used in conjunction withlithographic patterning tools or processes, for example, for thefabrication or manufacture of semiconductor devices, displays, LEDs,photovoltaic panels and the like. Typically, though not necessarily,such tools/processes will be used or conducted together in a commonfabrication facility. Lithographic patterning of a film typicallyincludes some or all of the following operations, each operation enabledwith a number of possible tools: (1) application of photoresist on aworkpiece, i.e., substrate, using a spin-on or spray-on tool; (2) curingof photoresist using a hot plate or furnace or UV curing tool; (3)exposing the photoresist to visible or UV or x-ray light with a toolsuch as a wafer stepper; (4) developing the resist so as to selectivelyremove resist and thereby pattern it using a tool such as a wet bench;(5) transferring the resist pattern into an underlying film or workpieceby using a dry or plasma-assisted etching tool; and (6) removing theresist using a tool such as an RF or microwave plasma resist stripper.

EXPERIMENTAL Experiment 1

A silicon oxide film was deposited on a substrate exposed to cycles ofthe following operations: exposure to a silicon-containing precursor,purging using argon, exposure to nitrogen plasma as a non-oxidizingplasma used for post-dose treatment, purging using argon, exposure tooxygen plasma, and purging using argon.

The deposition was performed at a pedestal temperature of 50° C. Thenitrogen plasma post-dose treatment was performed at varying plasmapowers as shown in Table 1 below and with various exposure times, wherethe exposure time is the duration of exposure to a single post-dosetreatment in one cycle of PEALD. The oxygen plasma used to convert thesilicon-containing precursor adsorbed onto the substrate to siliconoxide was generated at a power of 500 W, with each exposure to oxygenplasma lasting 0.3 seconds within each cycle. The deposition rate ofsilicon oxide per cycle was evaluated and is shown in Table 1.

TABLE 1 Deposition Rates Post Dose Plasma (N₂) RF Power RF TimeDeposition Rate (W) (s) (Å/cyc) 0 0.0 1.451 500 0.3 1.261 1000 0.3 1.2434000 0.3 1.151 4000 1.0 1.134 4000 3.0 0.962

A reduction in deposition rate was observed as plasma power and timeincreased, suggesting that silicon was removed after adsorption and/orsome densification of the deposited film was occurring.

Experment 2

A silicon oxide film was deposited on a substrate exposed to cycles ofthe following operations: exposure to a silicon-containing precursor,purging using argon, exposure to nitrogen plasma as a non-oxidizingplasma used for post-dose treatment, purging using argon, exposure tooxygen plasma, and purging using argon.

A second silicon oxide film was deposited on a substrate was exposed tocycles of the following operations: exposure to a silicon-containingprecursor, purging using argon, exposure to argon plasma as anon-oxidizing plasma used for post-dose treatment, purging using argon,exposure to oxygen plasma, and purging using argon.

The depositions were performed at a pedestal temperature of 400° C. Theplasma post-dose treatments were performed at varying plasma powers asshown in Table 2 below and with various exposure times, where theexposure time is the duration of exposure to a single post-dosetreatment in one cycle of PEALD. The oxygen plasma used to convert thesilicon-containing precursor adsorbed onto the substrate to siliconoxide was generated at a power of 4000 W, with each exposure to oxygenplasma lasting 0.25 seconds within each cycle.

The deposition rates of silicon oxide per cycle using nitrogen plasmaand using argon plasma as post-dose treatments were evaluated and areshown in Table 2.

TABLE 2 Nitrogen and Argon Plasma Post-Dose Treatments DepositionDeposition Post Dose Plasma Rate (Å/cyc) Rate (Å/cyc) RF Power (W) RFTime (s) N₂ Ar 0 0 0.843 0.839 500 0.3 0.837 0.836 1000 0.3 0.832 0.8321000 1 0.824 4000 0.25 0.783 4000 1 0.773 4000 3 0.758

Like Experiment 1, a reduction in deposition rate was observed as plasmapower and time increased, suggesting that silicon was removed afteradsorption and/or some densification of the deposited film was occurringin both processes. As compared to Experiment 1, which was conducted at alower temperature, the deposition rates in Experiment 2 were less thanthat of Experiment 1.

Experiment 3

A silicon oxide film was deposited on a substrate using cycles of thefollowing operations: exposure to a silicon-containing precursor,purging using argon, exposure to oxygen plasma, and purging using argon.This film was not deposited using a post-dose treatment.

Three substrates were exposed to cycles of the following operations:exposure to a silicon-containing precursor, purging using argon,exposure to nitrogen/oxygen plasma as a non-oxidizing plasma used forpost-dose treatment, purging using argon, exposure to oxygen plasma, andpurging using argon.

The depositions were performed at varying pedestal temperatures. Theplasma post-dose treatments were performed at 4000 W as shown in Table 3below and with various exposure times, where the exposure time is theduration of exposure to a single post-dose treatment in one cycle ofPEALD. The oxygen plasma used to convert the silicon-containingprecursor adsorbed onto the substrate to silicon oxide was generated ata power of 2000 W, with each exposure to oxygen plasma lasting 0.3seconds within each cycle for two trials, and lasting 3 seconds for

The deposition rates of silicon oxide per cycle using nitrogen plasma aspost-dose treatments and varying deposition temperatures were evaluatedand are shown in Table 3.

TABLE 3 Post-Dose Treatment Times and Pedestal Temperature Post DosePlasma RF Power RF Deposition Rate (Å/cycle) Plasma (W) Time (s) 300° C.200° C. 100° C. 50° C. 0 0 0.698 0.908 1.223 1.395 O₂ Plasma 4000 0.30.675 0.871 1.168 1.344 N₂ Plasma 4000 0.3 0.600 0.752 1.006 1.152 N₂Plasma 4000 3.0 0.538 0.651 0.832 0.938

Like Experiment 1, a reduction in deposition rate was observed as plasmapower and time increased, suggesting that silicon was removed afteradsorption and/or some densification of the deposited film was occurringin both processes. As compared to Experiment 1, which was conducted at alower temperature, the reduction in deposition rate is less than thereduction observed in Experiment 1. These results suggest that areas ofthe substrate exposed to the post-dose treatment, such as tops of highaspect ratio features, would result in a reduction in deposition rate,thereby preventing features from closing and forming a void. Suchresults suggest that post-dose treatments may be favorably used toprovide bottom-up growth of material in features.

A comparison of the second and third rows of Table 3, where the processconditions were the same except for the gas species used during thepost-dose treatment, shows that a non-oxidizing plasma removes adsorbedprecursor because the deposition rate using N₂ plasma was much lowerthan with O₂ plasma.

CONCLUSION

Although the foregoing embodiments have been described in some detailfor purposes of clarity of understanding, it will be apparent thatcertain changes and modifications may be practiced within the scope ofthe appended claims. It should be noted that there are many alternativeways of implementing the processes, systems, and apparatus of thepresent embodiments. Accordingly, the present embodiments are to beconsidered as illustrative and not restrictive, and the embodiments arenot to be limited to the details given herein.

What is claimed is:
 1. A method of processing a patterned substrate in aprocess chamber, the method comprising: (a) providing the patternedsubstrate having one or more features; (b) exposing the patternedsubstrate to a silicon-containing precursor under conditions allowingthe silicon-containing precursor to adsorb onto surfaces of the one ormore features, thereby forming an adsorbed layer of thesilicon-containing precursor over the patterned substrate; (c) beforeexposing the patterned substrate to a reactant to form asilicon-containing film and after exposing the patterned substrate tothe silicon-containing precursor, performing a post-dose treatmentoperation to preferentially remove the adsorbed layer at tops of the oneor more features; and (d) exposing the patterned substrate to thereactant and igniting a first plasma to form the silicon-containing filmover the patterned substrate.
 2. The method of claim 1, whereinperforming the post-dose treatment operation comprises exposing thepatterned substrate to a gas selected from the group consisting ofnitrogen, argon, hydrogen, ammonia, helium, and C_(x)H_(y), wherein x isan integer between and including 1-5 and y is an integer between andincluding 4-16.
 3. The method of claim 2, wherein performing thepost-dose treatment operation further comprises igniting a second plasmaat a plasma power less than about 6 kW.
 4. The method of claim 3,wherein performing the post-dose treatment operation further comprisesapplying a bias at a bias power between OW and 1000 W.
 5. The method ofclaim 1, wherein performing the post-dose treatment operation comprisesexposing the patterned substrate to ultraviolet radiation at awavelength between about 10 nm and about 400 nm.
 6. The method of claim1, wherein the post-dose treatment operation is performed for a durationbetween about 0.1 seconds and about 10 seconds.
 7. The method of claim1, wherein the patterned substrate is processed on a pedestal, and thesilicon-containing film is deposited and the post-dose treatmentoperation is performed at a pedestal temperature between about 25° C.and about 650° C.
 8. The method of claim 1, wherein thesilicon-containing film is selected from the group consisting of siliconoxide, silicon nitride, and silicon carbide.
 9. The method of claim 1,wherein the thickness of the silicon-containing film at the tops of theone or more features is less than the thickness of thesilicon-containing film at bottoms of the one or more features.
 10. Themethod of claim 1, wherein the one or more features have an aspect ratioof at least about 2:1.
 11. The method of claim 1, wherein at least oneof the one or more features has a feature opening is less than about5000 nm wide.
 12. The method of claim 1, further comprising repeating(a)-(d) for n cycles, where n is an integer greater than
 2. 13. Themethod of claim 1, wherein the process chamber is purged betweenperforming operations (b) and (c).
 14. The method of claim 1, whereinthe process chamber is purged between performing operations (c) and (d).15. A method of processing a patterned substrate, the method comprising:(a) providing a patterned substrate having one or more features; (b)exposing the substrate to a silicon-containing precursor underconditions allowing the silicon-containing precursor to adsorb ontosurfaces of the one or more features, thereby forming an adsorbed layerof the silicon-containing precursor over the patterned substrate; (c)before exposing the patterned substrate to a reactant to form a siliconoxide film and after exposing the patterned substrate to thesilicon-containing precursor, performing a post-dose treatment operationto preferentially remove the adsorbed layer at tops of the one or morefeatures, and (d) exposing the patterned substrate to anoxygen-containing reactant and igniting a first plasma to form thesilicon oxide film over the patterned substrate.
 16. The method of claim15, wherein performing the post-dose treatment operation comprisesexposing the patterned substrate to a non-oxidizing gas selected fromthe group consisting of nitrogen, argon, hydrogen, ammonia, helium, andC_(x)H_(y), wherein x is an integer between and including 1-5 and y isan integer between and including 4-16.
 17. The method of claim 16,wherein performing the post-dose treatment operation further comprisesigniting a second plasma at a plasma power less than about 6 kW.
 18. Themethod of claim 15, wherein performing the post-dose treatment operationcomprises exposing the patterned substrate to ultraviolet radiation at awavelength between about 10 nm and about 400 nm.
 19. An apparatus forprocessing substrates, the apparatus comprising: (a) at least oneprocess chamber including a pedestal for holding a substrate having oneor more features; (b) at least one outlet for coupling the at least oneprocess chamber to a vacuum; (c) one or more process gas inlets coupledto one or more silicon-containing precursor sources, one or morepost-dose treatment gas sources, and one or more reactant gas sources;(d) a radio frequency (RF) generator; and (e) a controller forcontrolling operations in the apparatus, including machine-readableinstructions for: (i) introducing a silicon-containing precursor from atleast one of the one of the one or more silicon-containing precursorsources to the at least one process chamber under conditions allowingthe silicon-containing precursor to adsorb onto the surface of thesubstrate, thereby forming an adsorbed layer of the silicon-containingprecursor over the substrate; (ii) prior to introducing a reactant fromat least one of the one or more reactant gas sources to the at least oneprocess chamber and after introducing the silicon-containing precursor,performing a post-dose treatment operation to remove adsorbedsilicon-containing precursor at tops of the one or more features of thesubstrate, and (iii) introducing the reactant and igniting a plasma toform a silicon-containing film over the substrate.